PNP switching transistor in a TO-18 metal package. NPN complements: BCY58 and BCY59. 3 BCY78; BCY79 PINNING PIN 1 2 3 emitter base collector, connected to case DESCRIPTION 1 handbook, halfpage 2 3 2 MAM263 1 Fig.1 Simplified outline (TO-18) and symbol. QUICK REFERENCE DATA SYMBOL VCBO PARAMETE.